In 1957 a sub-species of honey bee imported from Africa was released in Brazil. Since then, the African honey bee population has spread through South and Central America to southern Mexico. The Africanzied honey bee is expected to spread northward through the southern United States along the west coast into areas with moderate winter temperatures. The African honey bee has and, it is expected, will continue to interbreed with the North American or European honey bee. Herein lies the problem.
As it is used here, the term "African honey bee" or "AHB" includes "Africanized honey bees" and is meant to include pure African honey bees or European honey bees which have crossbred with African or Africanized honey bees and have thus become Africanized, i.e., developed African honey bee traits. The Africanized bees are descended from Apis mellifera scutellata, whose native country is the Savanna country of eastern and southern Africa. Pure African honey bees were originally imported to Brazil in an effort to improve that country's honey production. The beekeepers desired a bee better adapted to their hot, humid, tropical climate. Rinderer, Thomas E. (February 1986) American Bee Journal, pp. 98-100, 128-129 However, the introduction and spread of the African bees has resulted in the near collapse of the beekeeping industry in much of the South American community.
Unlike the more docile honey bees of generally European origin (also known as the American honey bee), which are predominant in the United States beekeeping industry, the Africanized bee has several undesirable characteristics which accounts for its identification in the media as the "killer bee". The Africanized bee is known for its relatively aggressive behavior and for its failure to establish stable hive locations. Further, the Africanized bee tends to supplant the European honey bee in any given area, for reasons not completely understood. When the European and African genetic material is mixed as a consequence of interbreeding, the hybridized bees tend to lose their European traits from generation to generation, perhaps by further cross-breeding with the dominant African strains. Reference is made to the following articles for a more detailed description of the characteristics of the Africanized bee: Taylor, Jr., 0.R. (Winter 1985) Bulletin of the Ent. Soc. Amer., Vol. 31, No. 4, pp. 14-24; Benson, K. (March 1985) American Bee Journal, pp. 188-191; Cobey, S. and T. Lawrence (September 1985) American Bee Journal, pp. 607-611; Rinderer, T.E. (February 1986) American Bee Journal, pp. 98-100, 128-129; Collins, A.M. & T.E. Rinderer (September 1986) American Bee Journal, pp. 623-627; Danka, R.G. & T.E. Rinderer (October 1986) American Bee Journal, pp. 680-683.
The potential consequences of the arrival of the Africanized bee to the beekeeping industry in a country are enormous. The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), which is responsible for keeping undesirable pests of plants and animals out of the United States, has determined that the Africanized bees could severely affect the queen-rearing industry, cause a drop in total production of honey, increase the operating costs of beekeeping, and force many beekeepers to go out of business or drop beekeeping as a hobby due to the aggressive nature of the Africanized bees and the restrictive ordinances applied to beekeeping. Stibick, Jeffrey N.L., (Winter 1984) Bulletin of the Ent. Soc. Amer., . 22-26. It has been estimated that the Amer., pp. 22-26. introduction of Africanized bees into the United States would result in an annual loss to the beekeeping industry of $26 to $58 million.
Additionally, the agricultural productivity of areas which are predominantly inhabited by Africanized bees is also expected to suffer. Pollination is the most critical phase in the production of many important food crops, and growers often rely upon honey bees to carry out pollination at a level which maximizes crop yields. The pollination value of honey bees in the U.S. alone has been estimated at $19 billion per year. Danka and Rinderer (supra).
In order to combat the migration and accidental importation of Africanized bees into northern Mexico, the United States, and Canada, commercial bee breeders will increasingly have the need to ascertain whether their bees do or do not carry Africanized genes. To accomplish this, it is important to be able to distinguish even hybridized (Africanized) bees from European bees.
The current most widely used method for identifying Africanized bees involves discriminant analysis of morphometric characteristics. Daly, H.V. and S.S. Balling (1978) J. Kans. Ent. Soc., Vol. 51, pp. 857-869; Daly, H.V., et al. (1982) Ann. Ent. Soc. Amer., Vol. 75, pp. 591-594; and Rinderer, et al. (1986) Apidologie, Vol. 17, pp. 33-48. Because Africanized bees are slightly smaller than European bees, morphometric measurements have been useful for identification of bees from distinct Africanized and European populations. However, measurements of phenotypic characters are subject to environmental influences and do not accurately identify low and intermediate levels of hybridization between the two honey bee populations and are also not statistically accurate for individual bees or very small colonies. Daly, et al. (supra).
The most commonly proposed alternative identification method is based on electrophoretic separation of discrete allozymes, i.e., slightly different enzymes that arise from alleles at the same locus. Mestriner, M.A. and E.P.B. Contel (1972) Genetics, Vol. 72, pp. 733-738; Martins, E., (1977) Biochem. Genetics, Vol. 15, pp. 357-366; Nunamaker, R.A. and W.T. Wilson (1981) J. Kans, Ent. Soc., Vol. 54, pp. 704-710; and Sylvester, H.A. (1982) J. Apic. Res., Vol. 21, pp. 93-97. Specific allozyme variants will approach Hardy-Weinberg equilibria within individual populations, and significant differences between non-interbreeding populations can be maintained. For example, allozymes have been successfully used as diagnostic characters for classifying individuals belonging to different non-interbreeding sibling species of Drosophila. Ayala, F.J. and J.R. Powell (1972) Proc. Nat. Acad. Sci., Vol. 69, pp. 1094-1096. With honey bees, however, there are overlapping and freely interbreeding populations. Computer simulations suggest that the diagnostic utility of specific allozyme variants will be rapidly lost with even low levels of gene exchange between honey bee populations. Page, R.E. and E.H. Erickson (1985) Ann. Ent. Soc. Amer., Vol. 78, pp. 149-158. The use of cuticular hydrocarbon analyses for identification of Africanized bees (Carlson, D.A. and A.B. Bolton, 1984, Bulletin of the Ent. Soc. Amer., Vol. 30, pp. 32-35) poses similar problems. Thus, there is still a tremendous need for an accurate method to determine whether a honey bee has become Africanized. Analyses of DNA restriction fragment polymorphisms have only recently been examined as a potential method for differentiating between honey bee subspecies. Hall, H.G. (1986) Proc. Nat. Acad. Sci., Vol. 83, pp. 4874-4877; Moritz, R.F.A., et al. (1986) Experimentia, Vol. 42, pp. 22-324. Because DNA molecules themselves are not subject to environmental influences, DNA probes offer an alternative to identification methods utilizing phenotypic characters. Further, because DNA polymorphisms are not limited to sequences expressed as proteins, they may not be as subject to evolutionary pressures. This may be especially important with honey bees because their haplodiploid mechanisms of sex determination (haploid males, diploid females) reportedly limits enzyme variability. Pamilo, P. (1978) Hereditas, Vol. 88, pp. 93-99.